A team takes a snapshot of a 500 GiB EBS volume, then a week later takes a second snapshot after only a small fraction of the data has changed. How does the storage behavior of the second snapshot compare to the first?
- The second snapshot is incremental, storing only the blocks that changed since the first snapshot, so it typically consumes far less storage than a full copy of the volume
- The second snapshot always duplicates the entire 500 GiB again, regardless of how little data changed
- The second snapshot only exists as a pointer and consumes no storage at all, since EBS snapshots after the first are always free
- The second snapshot's size depends entirely on the volume's provisioned IOPS setting, not on how much data changed
Why A? And why not the others?
Correct answer: A. The second snapshot is incremental, storing only the blocks that changed since the first snapshot, so it typically consumes far less storage than a full copy of the volume
Amazon EBS snapshots are incremental: the very first snapshot of a volume copies all of the volume's used blocks, but every snapshot taken after that stores only the blocks that have changed since the most recent snapshot, so a snapshot taken after only a small fraction of a 500 GiB volume changed will typically consume only a small amount of additional storage, not another full 500 GiB. The option claiming the second snapshot always duplicates the entire volume ignores this incremental design entirely and would make frequent snapshotting far more expensive than it actually is. The option claiming the second snapshot is entirely free and consumes no storage overstates the benefit: incremental snapshots still store the changed blocks and are billed for that storage, they simply avoid re-storing unchanged data. The option tying snapshot size to the volume's provisioned IOPS confuses a performance setting with a storage-usage question; IOPS provisioning has no bearing on how much data a snapshot needs to store.
Source: AWS EBS documentation: Amazon EBS snapshots — incremental snapshots